Greater Scaup

Aythya marila

The more northerly of our two scaup species, the Greater is also found across northern Europe and Asia. Winter flocks on coastal bays may number in the thousands. When a flock is feeding on waters where a tide is running, the birds generally face up-current; there may be a continuous shifting as birds from the back of the flock take off and fly to the front, so that the flock stays in roughly the same position despite the down-current tidal drift of individuals.

Conservation status

Populations have been declining significantly for the last few decades. The causes for these declines are not well understood, but pollution in coastal areas could be one factor.

Lakes, rivers, salt bays, estuaries. In summer on lakes and bogs in semi-open country near northern limits of boreal forest, and out onto tundra. In winter mainly on coastal bays, lagoons, estuaries; some on lakes inland. Overlaps with Lesser Scaup at all seasons, but in winter the Greater tends to be on more open bays, more exposed situations.

The more northerly of our two scaup species, the Greater is also found across northern Europe and Asia. Winter flocks on coastal bays may number in the thousands. When a flock is feeding on waters where a tide is running, the birds generally face up-current; there may be a continuous shifting as birds from the back of the flock take off and fly to the front, so that the flock stays in roughly the same position despite the down-current tidal drift of individuals.

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Feeding Behavior

Forages by diving and swimming underwater; large food items brought to surface to be eaten. Occasionally forages by dabbling or up-ending in shallow water. May feed at any time of day, or at night, with timing affected by tides in coastal regions.

Eggs

7-9, sometimes 5-11. Olive buff. Incubation is by female only, 24-28 days. Young: female leads young to water shortly after hatching; 2 or more broods may join, tended by 1 or more females. Young feed themselves, are capable of flight 40-45 days after hatching.

Young

Female leads young to water shortly after hatching; 2 or more broods may join, tended by 1 or more females. Young feed themselves, are capable of flight 40-45 days after hatching.

Diet

Mostly mollusks and plant material. Diet in winter is mainly mussels, clams, oysters, snails, and other mollusks. In summer (and perhaps in winter on fresh water) consumes plants including pondweeds, wild celery, sedges, grasses, and others; also insects and crustaceans.

Nesting

Pair formation occurs mostly in late winter and early spring. Several males may court one female. Display elements of the males include throwing the head back sharply while giving a soft call; exaggerated bowing movements, with bill tip lowered to water and then raised high; flicking wings and tail while giving soft whistled notes. Nest site usually very close to water on island, shoreline, or mats of floating vegetation. Nest is a shallow depression, lined with dead plant material and with down. Female chooses nest site and builds nest. Several nests may be close together in loose colony.

Migration

Migrates in flocks. Birds from Alaska may winter on either Pacific or Atlantic coast; banding records indicate that the same individual may go to opposite coasts in different winters, probably as a result of joining different flocks.

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Migration

Migrates in flocks. Birds from Alaska may winter on either Pacific or Atlantic coast; banding records indicate that the same individual may go to opposite coasts in different winters, probably as a result of joining different flocks.

How climate change could affect this bird's range

In the broadest and most detailed study of its kind, Audubon scientists have used hundreds of thousands of citizen-science observations and sophisticated climate models to predict how birds in the U.S. and Canada will react to climate change.

Greater Scaup

Each map is a visual guide to where a particular bird species may find the climate conditions it needs to survive in the future. We call this the bird’s “climatic range.”

The colors indicate the season in which the bird may find suitable conditions— blue for winter, yellow for summer (breeding), and green for where they overlap (indicating their presence year-round).

The darker the shaded area, the more likely it is the bird species will find suitable climate conditions to survive there.

The outline of the approximate current range for each season remains fixed in each frame, allowing you to compare how the range will expand, contract, or shift in the future.

The first frame of the animation shows where the bird can find a suitable climate today (based on data from 2000). The next three frames predict where this bird’s suitable climate may shift in the future—one frame each for 2020, 2050, and 2080.

You can play or pause the animation with the orange button in the lower left, or select an individual frame to study by clicking on its year.

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season. More on reading these maps.